Genetic and metabolic contributions of articular chondrocytes to degenerative joint disease and disturbed skeletal growth are approached through culture methods. There are major species differences in the in vitro behavior of mammalian articular chondrocytes. Employing recently developed techniques for growing human cells, aging of these as well as rabbit chondrocytes will be studied. The response of growth plate chondrocytes to Chondrocyte Growth Factor, a contaminant of pituitary glycoprotein hormones, in investigated in organ and cell culture in normal and chondrodystrophic mutant rabbits. The feasibility of experimental siderosis of cultured chondrocytes as a model for hemophilic arthropathy is being tested.